Simulation Study On Influence Of 9m Minimum Control Water Level Dispatching Plan Of Poyang Lake Water Control Project On Water Environment

In order to study the impact of the proposed Poyang Lake Water Conservancy Project on the water environment of the Poyang Lake,the two-dimensional hydrodynamic water quality model of the Poyang Lake is used to simulate the scenario in typical years of high water year(2012),low water year(2007)and flat water year(2008)according to the planned dispatching scheme of the Poyang Lake Water Conservancy Project.The concentration changes of TN and TP were analyzed in space.The results show that:(1)High water year(2012)with a hub in the scene,the average concentration of TN lake upstream,midstream,downstream year decline 0.93%,0.33%,0.40%;water-quality improvement effect better than the upstream and downstream midstream;September-December and January-March TN concentration decreased;average concentration of TP in the lake upstream,midstream,downstream year decline 1.87%,2.96%,1.28%,improvement of water quality better than the middle of the downstream and upstream effects,January-March water-quality improvement effect better than that from September to December and April to August;spatially Lakes region hub and hub to no water-based III and IV class,scheduling of TN concentration becomes good hub obvious;there hub In the non-hub lake area,the type II water or the type III water is the main one.In the connecting period of the rivers and lakes,the TP concentration increases obviously in the Ganjiang River and the Xiuhe River estuary;the TP concentration decreases in the northern part of the lake and the river connecting area,at the hub During the dispatch period,the decline between the lake and the river is more obvious.(2)Low water year(2007)of the hub has a lower profile,the average concentration of TN Lake upstream,midstream,downstream year decline 1.42%-3.00%-9.25%,better than the effect of improving the upstream and downstream midstream;April The concentration of TN increased in August;the concentration of TN decreased in September-December and January-March;The average annual concentration of TP decreased by 9.5%,18.48% and 9.57% in the upper,middle and lower reaches of the Lake District.The improvement of water quality is better than the improvement of water quality in the upstream and middle reaches.In the case of hubs from September to December,the water quality improved significantly,followed by January-March,and the water quality improvement was not obvious from April to August.In space,there was no hub in the hub with type II water and type III water,hub scheduling period,lake and river junction area And the water concentration in the southern part of the lake area was significantly reduced.The water quality concentration increased significantly in the Tangying,Banghu Lake and the Songmenshan area.;there is a hub-free lake area with a type III water.In the period of rivers and lakes,the TP concentration does not change much;in other periods,the overall concentration of TP decreases.(3)Flat water year(2008)in there hub scenario,the average concentration of TN in the lake upstream,midstream,decrease the downstream up 4.36%,-0.88%,2.76%,water upstream of better than quality improvement downstream and intermediate results better;April to August and September to December there is no hub than the hub TN concentration decreased,from January to March increased water concentration;The average annual concentration of TP decreases by 15.40% and 21.84 in the upper,middle and lower reaches of the lake.%,17.03%,the water quality improvement in the middle reaches is better than the upstream and middle water quality improvement;in the January-April and September-December scenarios,the water quality is significantly improved.In space,there are hubless hubs with type II water and type III water.In the connected period of rivers and lakes,type I water appears,and the overall TN concentration of the lake decreases.In the space,there is a hub-free main lake area III Water-like or type IV water is dominant,and the change of TP concentration is obvious from September 1st to October 31 st,from the non-junction type III water to the hub type II water;in other periods,the lake and river connection area is reduced.(4)Under three typical years,when there is a hub,the concentration of TN in the high water year is decreasing in the whole lake area,and the decline in the year of low and flat water year is not obvious;the concentration of TP is decreased in the three typical years.The decrease of TP concentration in flat water year was the most obvious;the decrease of TN and TP was the most obvious in January-March;the change of TN and TP in the junction area between lake and river was obvious;the improvement effect of TP was better than TN.